| 1 | <HTML> |
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| 2 | <!-- |
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| 3 | -- Copyright (c) Jeremy Siek 2000 |
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| 4 | -- |
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| 5 | -- Distributed under the Boost Software License, Version 1.0. |
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| 6 | -- (See accompanying file LICENSE_1_0.txt or copy at |
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| 7 | -- http://www.boost.org/LICENSE_1_0.txt) |
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| 8 | --> |
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| 9 | <Head> |
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| 10 | <Title>Boost Graph Library: Depth-First Visit</Title> |
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| 11 | <BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" |
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| 12 | ALINK="#ff0000"> |
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| 13 | <IMG SRC="../../../boost.png" |
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| 14 | ALT="C++ Boost" width="277" height="86"> |
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| 15 | |
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| 16 | <BR Clear> |
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| 17 | |
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| 18 | <H2><A NAME="sec:dfs"></A> |
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| 19 | <img src="figs/python.gif" alt="(Python)"/> |
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| 20 | <TT>depth_first_visit</TT> |
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| 21 | </H2> |
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| 22 | |
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| 23 | |
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| 24 | <P> |
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| 25 | <PRE> |
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| 26 | template <class <a href="./IncidenceGraph.html">IncidenceGraph</a>, class <a href="./DFSVisitor.html">DFSVisitor</a>, class ColorMap> |
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| 27 | void depth_first_visit(IncidenceGraph& g, |
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| 28 | typename graph_traits<IncidenceGraph>::vertex_descriptor s, |
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| 29 | DFSVisitor& vis, ColorMap color) |
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| 30 | |
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| 31 | template <class <a href="./IncidenceGraph.html">IncidenceGraph</a>, class <a href="./DFSVisitor.html">DFSVisitor</a>, class ColorMap, |
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| 32 | class TerminatorFunc> |
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| 33 | void depth_first_visit(IncidenceGraph& g, |
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| 34 | typename graph_traits<IncidenceGraph>::vertex_descriptor s, |
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| 35 | DFSVisitor& vis, ColorMap color, TerminatorFunc func = TerminatorFunc()) |
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| 36 | </PRE> |
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| 37 | |
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| 38 | <P> |
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| 39 | This function visits all of the vertices in the same connected |
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| 40 | component as the source vertex <tt>s</tt>, using the <a |
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| 41 | href="./graph_theory_review.html#sec:dfs-algorithm">depth-first |
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| 42 | pattern</a>. The main purpose of the function is for the |
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| 43 | implementation of <TT>depth_first_search()</TT> though sometimes it is |
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| 44 | useful on its own. |
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| 45 | |
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| 46 | <p> |
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| 47 | The <tt>DFSVisitor</tt> supplied by the user determines what |
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| 48 | actions are taken at each event-point within the algorithm. |
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| 49 | |
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| 50 | <p> |
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| 51 | The <tt>ColorMap</tt> is used by the algorithm to keep track |
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| 52 | of which vertices have been visited. |
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| 53 | |
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| 54 | <p>The second variant can be used, for example, to find all marked vertices |
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| 55 | reachable from a start vertex by a path which does not contain any another |
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| 56 | marked vertices. |
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| 57 | |
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| 58 | |
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| 59 | <P> |
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| 60 | |
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| 61 | <h3>Where Defined:</h3> |
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| 62 | |
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| 63 | <a href="../../../boost/graph/depth_first_search.hpp"><TT>boost/graph/depth_first_search.hpp</TT></a> |
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| 64 | |
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| 65 | |
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| 66 | <h3>Parameters</h3> |
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| 67 | |
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| 68 | IN <tt>IncidenceGraph& g</tt> |
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| 69 | <blockquote> |
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| 70 | A directed or undirected graph. The graph's type must be a model of |
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| 71 | <a href="./IncidenceGraph.html">Incidence Graph</a>.<br> |
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| 72 | |
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| 73 | <b>Python</b>: The parameter is named <tt>graph</tt>. |
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| 74 | </blockquote> |
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| 75 | |
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| 76 | IN: <tt>vertex_descriptor s</tt> |
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| 77 | <blockquote> |
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| 78 | The source vertex from which to start the search.<br> |
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| 79 | |
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| 80 | <b>Python</b>: The parameter is named <tt>root_vertex</tt>. |
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| 81 | </blockquote> |
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| 82 | |
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| 83 | IN: <tt>DFSVisitor visitor</tt> |
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| 84 | <blockquote> |
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| 85 | A visitor object that is invoked inside the algorithm at the |
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| 86 | event-points specified by the <a href="./DFSVisitor.html">DFS |
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| 87 | Visitor</a> concept. The visitor object is passed by value <a |
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| 88 | href="#1">[1]</a>.<br> |
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| 89 | |
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| 90 | <b>Python</b>: The parameter should be an object that derives from |
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| 91 | the <a href="DFSVisitor.html#python"><tt>DFSVisitor</tt></a> type of |
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| 92 | the graph. |
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| 93 | </blockquote> |
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| 94 | |
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| 95 | UTIL: <tt>ColorMap color</tt> |
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| 96 | <blockquote> |
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| 97 | This is used by the algorithm to keep track of its progress through |
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| 98 | the graph. The type <tt>ColorMap</tt> must be a model of <a |
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| 99 | href="../../property_map/ReadWritePropertyMap.html">Read/Write |
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| 100 | Property Map</a> and its key type must be the graph's vertex |
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| 101 | descriptor type and the value type of the color map map must model |
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| 102 | <a href="./ColorValue.html">Color Value</a>.<br> |
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| 103 | |
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| 104 | <b>Python</b>: The color map must be a <tt>vertex_color_map</tt> for |
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| 105 | the graph. |
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| 106 | </blockquote> |
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| 107 | |
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| 108 | IN: <tt>TerminatorFunc func</tt> |
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| 109 | <blockquote> |
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| 110 | A function object callable with two parameters - the descriptor of |
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| 111 | vertex and the graph instance - and returning bool. The call is made |
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| 112 | immediately after call to 'discover_vertex' visitor |
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| 113 | event. If <tt>true</tt> is returned, the out edges of the vertex are |
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| 114 | not examined, as if they don't exist.<br> |
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| 115 | |
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| 116 | <b>Python</b>: Unsupported parameter. |
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| 117 | </blockquote> |
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| 118 | <P> |
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| 119 | |
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| 120 | <h3>Complexity</h3> |
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| 121 | |
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| 122 | Time complexity is <i>O(E)</i>. |
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| 123 | |
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| 124 | |
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| 125 | <h3>Notes</h3> |
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| 126 | |
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| 127 | <p><a name="1">[1]</a> |
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| 128 | Since the visitor parameter is passed by value, if your visitor |
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| 129 | contains state then any changes to the state during the algorithm |
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| 130 | will be made to a copy of the visitor object, not the visitor object |
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| 131 | passed in. Therefore you may want the visitor to hold this state by |
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| 132 | pointer or reference. |
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| 133 | |
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| 134 | |
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| 135 | <br> |
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| 136 | <HR> |
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| 137 | <TABLE> |
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| 138 | <TR valign=top> |
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| 139 | <TD nowrap>Copyright © 2000-2001</TD><TD> |
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| 140 | <A HREF="../../../people/jeremy_siek.htm">Jeremy Siek</A>, Indiana University (<A HREF="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</A>) |
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| 141 | </TD></TR></TABLE> |
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| 142 | |
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| 143 | </BODY> |
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| 144 | </HTML> |
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